I decided to try to make my own chain stakes and it turns out they were simple, yet worked great. I used 3/8th black pipe cut on a 45 degree angle at 3" long. I dropped a nut in the plugged end and filled it with weld to keep dirt from plugging up the end and causing my driver to stick
I bent my first link of #3 chain to nearly a 90 degree bend, tack welded it to the top front of the pipe, smacked it with a hammer to a true 90 when it was hot (so the link wouldn't crack), and fully welded the link to the pipe. This eliminates any need for drilling or using a rivet, a nut, or an S-hook. This connection is super strong and low profile. I really like it so far as they set everytime and hold like....well...a chain.
I welded a short piece of pipe with the same 45 degree cut to the end of my driver. The driver is 5/8" grade 8 all thread with the end ground down to fit inside the pipe. This has been by far the best driver I've ever used. I usually go through at least 6 "cold rolled" drivers a season, but this one is still straight as an arrow after driving superstakes all last year. I beat the snot out of that driver. Find some grade 8 material and add a soft grade 5 nut to the top to wail on.
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I also thought of welding a fender washer to the bottom of the pipe for more holding power in soft ground or mud, but so far it has not been needed. It would sort of be like a finned stake. You could also weld a nut to the back side for a retrieval boss.